Identification notes
This is a common and usually conspicuous pleurocarpous moss of fast-flowing base-poor watercourses in hilly areas of the north and west. It’s absent from much of the lowlands, though.
Like many riparian mosses, it is variable in form and sometimes needs to be checked closely to make sure it’s not Ctenidium molluscum, which sometimes grows on riverbanks or even, (when a bit straggly) Scuiro-hypnum plumosum, another highly variable moss.
Unlike S-h. plumosum, H. armoricum prefers riparian zones where it is always wet but where it is not exposed to the shearing forces of high, fast flows. So it is frequently found in bank flushes, rivulets, in the spray/mist zone of waterfalls and at the water’s edge.
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